Early automatic machine tool controllers incorporated a limited number of functions, wherein the operators could quickly and rapidly familiarize themselves and operate the machine tool to its capacity of control in a short time. However, the increasing complexity of the controllers required a corresponding increase in the learning time necessary to operate the equipment. Moreover, each particular machine tool incorporated its own conventions for the functions, such that learning the details of the operational features of each machine is significant for the efficient and accurate machine tool operation. Also, the features and operation of one machine would not necessarily be useful in another machine. As the machine tool controllers incorporated programmable control, the machine tool efficiency and reliability initially suffers due to the increasing complexity and uniqueness of design of each machine tool controller. Further technological change accelerates opportunities for problems to the point that improvements often are offset by system hardware or software errors, as well as detailed operator training.
A standard useful in the machine tool industry is the STD bus format of signal and data transfer, a particular form of computer data transfer. However, the mere application of a computer system incorporating the STD bus to machine tool controllers merely reiterates the above-discussed problems in another form, merely giving the appearance of improved machine tool controller design or ease of operation. Typically, the selection of STD bus-compatible devices, such as listed in the STD Bus Buyers Guide, published by the Ironoak Company of La Jolla, Calif., 1983, provides system control elements wherein the machine tool functions are primarily calculated in the central machine tool controller system processor. Such centralized control of system functions is adequate for small or custom systems, wherein the time necessary for accurate machine tool control is sufficient, or can be compensated for by techniques known in the art. However, modern machine tool controllers are frequently custom-configured according to changing customer requirements. As the number of control functions (axes) increase or the resolution of time or instruction signal is increased, the centralized system control may no longer be adequate for use as the machine tool controller. In such case, redundant central systems, perhaps connected together for coordination of operations, are often required to perform the required machine tool operation. However, such multiple application provides limited consistency in design and reliability in operation. As a result, the advantages gained in coordinated processor machine tool control systems are lost due to development costs and limitations of initial reliability.